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任務(wù)書(shū) 一、原始依據(jù)（包括設(shè)計(jì)或論文的工作基礎(chǔ)、研究條件、應(yīng)用環(huán)境、工作目的等。） 根據(jù)相關(guān)設(shè)計(jì)資料，確定合理的工藝方案，使給水廠出水水質(zhì)達(dá)到《生活飲用水衛(wèi)生標(biāo)準(zhǔn)》（GB5749-2006），并安全輸配到用戶，滿足用戶的需求。 （1）設(shè)計(jì)水量：滿足最高日供水量 8 ×104m3/d。 （2）原水水質(zhì)：各項(xiàng)指標(biāo)達(dá)到地表水環(huán)境質(zhì)量標(biāo)準(zhǔn)（GB 3838-2002)中的Ⅱ類水質(zhì)標(biāo)準(zhǔn)； （3）氣象水文資料： 1）氣溫：全年平均氣溫6.5；最冷月平均最低氣溫－18.5；最熱月平均最高29.5；極端最高氣溫38.4；極端最低氣溫－31.4； 2） 降雨量：年降雨量308.9mm；最大時(shí)降雨量33.1mm；最大日降雨量100.8mm； 3）風(fēng)向與風(fēng)速：年最多風(fēng)向北風(fēng)； 夏季：東風(fēng)、東南風(fēng)； 冬季：北風(fēng)、西北風(fēng)；夏季平均風(fēng)速3.3m/s；冬季平均風(fēng)速3.2 m/s；夏季最多風(fēng)向頻率15；冬季最多風(fēng)向頻率17； 4）最大積雪深度21mm；冰凍期150 天； 5）氣壓：大氣壓888.4毫巴； 6）相對(duì)濕度：冬季空氣調(diào)節(jié)54％；最熱月平均58％； 7）蒸發(fā)量：年蒸發(fā)量2324.2毫米。 （4）工程地質(zhì)資料： 地下水位深度170厘米，最大冰凍深度170厘米； 土壤承載力滿足基建設(shè)計(jì)要求。 （5）二泵站輸水管起端節(jié)點(diǎn)水壓 46 m。 學(xué)生在畢業(yè)設(shè)計(jì)過(guò)程中熟悉相關(guān)的工作方法、工作過(guò)程，掌握主體工藝的設(shè)計(jì)計(jì)算和繪圖，加強(qiáng)對(duì)所學(xué)基礎(chǔ)知識(shí)的應(yīng)用技能，為日后工作打下堅(jiān)實(shí)基礎(chǔ)。 二、參考文獻(xiàn) [1] 陳培康.給水凈化新工藝[M]．北京:學(xué)術(shù)書(shū)刊出版社，1990. [2] 許保玖.給水處理理論與設(shè)計(jì)[M]．北京:中國(guó)建筑工業(yè)出版社，1992. [3] 金兆豐.21世紀(jì)的水處理[M]．北京:化學(xué)工業(yè)出版社，2003. [4] 丁亞蘭．國(guó)內(nèi)外給水工程設(shè)計(jì)實(shí)例[M]．北京：化學(xué)工業(yè)出版社，1999. [5] 崔玉川．凈水廠設(shè)計(jì)知識(shí)[M]．北京：中國(guó)建筑工業(yè)出版社，1987. [6] 鐘淳昌.凈水廠設(shè)計(jì)[M]．北京:中國(guó)建筑工業(yè)出版社，1986. [7] 陸柱．水處理技術(shù)[M]．上海：華東理工大學(xué)出版社，2000. [8] 高湘．給水工程技術(shù)及工程實(shí)例[M]．北京：化學(xué)工業(yè)出版社，2002. [9] 王業(yè)俊.水處理手冊(cè)[M]．北京:中國(guó)建筑工業(yè)出版社，1983. [10] 鐘淳昌.簡(jiǎn)明給水設(shè)計(jì)手冊(cè)[M]．北京:中國(guó)建筑工業(yè)出版社，1989. [11] 張啟海.城市給水工程[M]．北京:中國(guó)水利水電出版社，2003. [12] 楊松林.水處理工程CAD技術(shù)應(yīng)用及實(shí)例[M]．北京:化學(xué)工業(yè)出版社,2001. [13] 姜乃昌.水泵及水泵站[M]．北京:中國(guó)建筑工業(yè)出版社,1989. [14] 崔玉川.給水廠處理設(shè)施設(shè)計(jì)計(jì)算[M]．北京:化學(xué)工業(yè)出版社,2002. [15] 中國(guó)給水排水[J].專業(yè)期刊. [16] 給水排水[J].專業(yè)期刊 三、設(shè)計(jì)（研究）內(nèi)容和要求（包括設(shè)計(jì)或研究?jī)?nèi)容、主要指標(biāo)與技術(shù)參數(shù)，并根據(jù)課題性質(zhì)對(duì)學(xué)生提出具體要求。） 1．設(shè)計(jì)內(nèi)容要求 （1）根據(jù)水質(zhì)、水量、地區(qū)條件、施工條件和水廠運(yùn)行情況、確定凈水廠的處理工藝流程； （2）擬定各處理構(gòu)筑物的設(shè)計(jì)流量，并根據(jù)確定的凈水廠位置，選擇適宜采用的處理構(gòu)筑物，確定設(shè)計(jì)采用的處理構(gòu)筑物的形式及數(shù)量； （3）進(jìn)行各構(gòu)筑物的設(shè)計(jì)計(jì)算，確定各構(gòu)筑物和各主要構(gòu)件的尺寸并繪制部分計(jì)算簡(jiǎn)圖，設(shè)計(jì)時(shí)要考慮到構(gòu)筑物及其構(gòu)件施工上的可能性，并符合要求。 1）投藥及混合 根據(jù)原水水質(zhì)、處理要求、貨源及其他經(jīng)濟(jì)技術(shù)條件選定混凝劑品種及投加量，設(shè)計(jì)溶解池、溶液池，布置加藥間及藥庫(kù)，畫(huà)出草圖；確定混合方式，進(jìn)行混合工藝設(shè)計(jì)計(jì)算和設(shè)備選擇。 2）絮凝、沉淀（或澄清池） 絮凝池和沉淀池應(yīng)同時(shí)進(jìn)行計(jì)算和設(shè)計(jì)，并應(yīng)注意兩者的關(guān)系與配合，要使兩池之間在高程、水流銜接、深度和池?cái)?shù)等方面相互配合。根據(jù)設(shè)計(jì)流量，絮凝池、沉淀池應(yīng)至少分為獨(dú)立相同的兩組，每組可根據(jù)需要分為若干格。也可根據(jù)水質(zhì)情況選用澄清池，并進(jìn)行設(shè)計(jì)計(jì)算。 3）濾池 在北方，濾池一般應(yīng)設(shè)在室內(nèi)，沖洗水泵房應(yīng)盡可能與濾池合建。 4）消毒 選定消毒劑并根據(jù)水質(zhì)有關(guān)參考資料確定其投加量，投加點(diǎn)應(yīng)根據(jù)水質(zhì)情況確定。進(jìn)一步選擇投加設(shè)備，布置加藥間及藥庫(kù)，繪出草圖。 5）清水池 清水池之間要既能互相連通，又能單池運(yùn)行。清水池應(yīng)根據(jù)水量大小、地形及設(shè)計(jì)高程而定，由單池容積和設(shè)計(jì)水深決定水池平面尺寸。 （4）根據(jù)各構(gòu)筑物的確定尺寸，確定各構(gòu)筑物在平面位置上的確切位置，完成平面布置；確定各構(gòu)筑物間聯(lián)接管道的位置，管徑、長(zhǎng)度、材料及附屬設(shè)施，完成水廠的高程布置。 （5）繪制凈水廠平面及高程布置圖，凈水構(gòu)筑物工藝平、剖面圖。 （6）二泵站設(shè)計(jì)計(jì)算 選泵臺(tái)數(shù)不宜過(guò)多，也不宜過(guò)少，應(yīng)能滿足各種不同流量及揚(yáng)程之需要為宜，一般4-7臺(tái)，盡可能同型號(hào)。確定泵站形式，進(jìn)行泵站設(shè)計(jì)計(jì)算；繪制二泵站工藝圖。 2．設(shè)計(jì)成果要求 （1）設(shè)計(jì)說(shuō)明書(shū)一份（≮1.2萬(wàn)字）；參考文獻(xiàn)≮10篇；相關(guān)外文文獻(xiàn)資料翻譯1份（≮5000漢字）。 （2）繪制的圖紙折合零號(hào)圖紙≮3張。 指導(dǎo)教師（簽字） 年 月 日 審題小組組長(zhǎng)（簽字） 年 月 日 外文資料 Effects of pH on coagulation behavior and floc properties in YellowRiver water treatment using ferric based coagulants CAO BaiChuan1, GAO BaoYu1*, XU ChunHua1, FU Ying2 & LIU Xin1 1 Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China; 2 School of Civil and Architecture, Jinan University, Jinan 250022, China Received June 13, 2009; accepted October 19, 2009 Enhanced coagulation is one of the major methods to control disinfection by-products (DBPs) in water treatment process. Coagulation pH is an important factor that affects the enhanced coagulation. Recently, many studies focus on the coagulation effects andmechanisms, and few researchers studied the properties of flocs formed under different coagulation pH. Two inorganic polymercoagulants, polyferric silicate sulphate (PFSS) and polyferric sulphate (PFS), were used in Yellow River water treatment. The influence of pH on coagulation effect was investigated under the optimum dosage, and the results show that both coagulants gave excellent organism removal efficiency when pH was 5.50. According to the variation of zeta potential in coagulation process, coagulation mechanisms of the coagulants were analyzed. An on-line laser scatter instrument was used to record the development of floc sizes during the coagulation period. For PFSS, pH exerted great influence on floc growth rates but little influence on formed floc sizes. In PFS coagulation process, when pH was 4.00, PFS flocs did not reach the steady-state during the whole coagulation period, while little difference was observed in floc formation when pH was 5.50 and above. The preformed flocs were exposed to strong shear force, and the variation of floc sizes was determined to evaluate the influence of pH on floc strength and re-growth capability. In comparison of the two coagulants, PFS flocs had higher floc strength and better recovery capability when pH was 4.00, while PFSS flocs had higher floc strength but weaker recovery capability when pH was 5.50 and above. ferric based inorganic polymer coagulants, pH, coagulation effect, floc formation, floc breakage and re-growth behavior and floc properties in Yellow River water treatment using ferric based coagulants. Chinese Sci Bull, 2010, 55: 1382?1387, doi: 10.1007/s11434-010-0087-5 Enhanced coagulation is one of the processes recommended by USEPA to remove natural organic matters (NOM) in surface water and to control disinfection by-products (DBPs) [1]. The development of new types of coagulants with high coagulation effect is one of the hot topics in the field of enhanced coagulation [2]. In the field of drinking water treatment, many studies focus on ferric based inorganic polymer coagulants, because of their advantages in removing dissolved organic compounds, such as high removal efficiency, low bio-toxicity, high coagulation rate and large flocs, excellent sedimentation and dewatering abilities [3]. Polyferric silicate sulphate (PFSS) and polyferric sulphate (PFS) are two kinds of typical coagulants [4,5], which can achieve good removal of natural organic compounds. As the ferric coagulants are dosed, the organic compounds in surface water are removed in the following ways [6]. The coagulants may react with the functional groups of organic compounds to form complexes or chelates, and part of the organic compounds could be captured by absorption and sweep flocculation. The coagulation pH is one of the main factors that influence the removal effect of enhanced coagulation, and for ferric coagulants the optimum pH range is 5.5?6.5 [7]. Floc breakage is accompanied with the growth and transmission of flocs in coagulation process, and the fragCAOBaiChuan, et al. Chinese Sci Bull May (2010) Vol.55 No.14 1383 mentation of flocs influences the efficiency of solid/liquid separation and follow-up treatment processes [8]. The degree of floc breakage is related to the applied shear force, shear period and floc strength. Under smaller hydrodynamic conditions, the broken flocs have certain capability for re-growth.The extent of re-growth depends on the mechanism of floc formation [9,10].Recently, many studies focused on the breakage and re-growth capability of flocs formed by traditional inorganic coagulants [11,12], and there have been reports about researches on the floc properties of organic flocculants and polyaluminum chloride [10,13]. For ferric based inorganic polymer coagulants, Wei et al. [14] studied the size distribution and fractal of flocs of polyferric chloride and different polyferric-cationic polymer dual-coagulant in humic acid solution. Fu et al. [15] quantitatively studied the size distribution of residual particles and the influence of turbulent shear on the flocs in the poly-silicic-ferric coagulation process. There has been no report about the influence of pH on floc formation, floc breakage and re-growth capability for ferric polymer coagulants. Two inorganic polymer coagulants, polyferric silicate sulphate (PFSS) and polyferric sulphate (PFS), were selected in this study to treat the Yellow River water, and the influence of pH on coagulation effects was investigated. A laser diffraction particle size analyzer was used to determine the particle size of flocs on-line, and the floc formation process, floc breakage and re-growth capability were evaluated under different pH conditions. 1 Materials and methods 1.1 Materials All reagents used were analytical grade chemicals. Deionized water was used to prepare all solutions.The raw water used in the study was sampled from Luokou section of the Yellow River in November 2008, and it is characterized by high turbidity, high organic carbon and high alkalinity. The raw water was allowed to settle for 24 h, and the supernatant was then withdrawn by siphon from about 20 cm below the water surface and stored in refrigerator for subsequent test. The properties of the supernatant are as follows: temperature=12.4?13.0°C, pH = 8.07?8.23, turbidity= 11.3?13.0 NTU, UV254=0.049?0.057 cm?1, hardness=260.3?291.4 mg CaCO3/L. 1.2 Preparation of coagulants PFSS was prepared using polysilicic acid (PS), FeSO4·7H2O and NaClO3 as raw materials. First, PS solution with a SiO2 concentration of 5% (w/w) was prepared as follows:14.20 g Na2SiO3·9H2O was dissolved in 70 mL deionized water and then introduced slowly to H2SO4 solution (1:3) under magnetic stirring at room temperature to obtain a polysilicic acid solution (PS). The pH of the system was controlled at 1.50 and the PS solution was aged for 2 h.Then, 13.90 g FeSO4·7H2O was added to the PS solution to yield the Si/Fe ratio 1:1, and mixed rapidly at 40°C. Subsequently, 0.89 g NaClO3 was added as an oxidant. PFSS samples were taken out after 3 h’ aging, and then were diluted to 10 g Fe/L.Commercial solid polyferric sulfate (PFS, Fe concentration: 21% (w/w), B=12%) was purchased from Zibo Tianshui Chemical Industrial Co., Ltd, China. 1.3 Coagulation test Coagulation tests were conducted on a jar tester (ZR4-6, Zhongrun Water Industry Technology Development Co.Ltd., China). One liter of water was transferred into each beaker. The jar test involved 1 min rapid mix at 200 r/min, a 15 min 40 r/min coagulation stage, and a 15-min settlement period. The samples was collected from 2 cm below the surface and a portion was filtered through a 0.45 μm membrane to measure the absorbance at 254 nm wavelength (UV254) using a JH-752 UV/VIS spectrophotometer (Jinghua Scientific Instrument Co. Ltd., Shanghai, China). The residual turbidity was measured via a 2100P turbidimeter (Hach Co. US), and a Zetasizer 3000HSa (Malvern Instruments, UK) was used to measure the zeta potential. 1.4 Floc breakage and re-growth A 15 min stirring phase at 200 r/min was introduced following the flocculation phase, and the preformed flocs were broken. After the breakage period, a slow stir at 40 r/min was reintroduced for a further 15 min to allow flocs reaggregation. The variation of floc sizes was recorded on-line via a laser diffraction instrument Mastersizer 2000 (Malvern). 2 Results and discussion 2.1 Influence of pH on coagulation effects Initially, coagulation optimization tests were carried out to ascertain the optimum dosage for turbidity and UV254 removal under the initial pH. For both of the coagulants used in this study, the results show that excellent turbidity removal effects were obtained at lower coagulants dosages. PFS gave optimum UV254 removal in the dosage region of 8?12 mg/L, and the highest UV254 removal efficiency of PFSS occurred when the dosage was 9?12 mg/L. Therefore, the 10 mg/L coagulant dosage was chosen for all the subsequent experiments. HCl and NaOH solutions with concentrations of 0.1 and 0.01 mol/L were used to adjust the sample pH, and the 1384 CAO BaiChuan, et al. Chinese Sci Bull May (2010) Vol.55 No.14 coagulation experiments were carried out on the jar tester with the coagulant dosage of 10 mg/L. Figure 1 shows the variation of UV254 and turbidity removal efficiencies under the influence of pH. It was found that, for both of the coagulants, the residual turbidity of the effluence decreased with the increasing pH. When the coagulation pH was higher than 5.50, the residual turbidity dropped below 1 NTU. For UV254 removal, when the coagulation pH was less than 5.50, the removal efficiency of each coagulants increased as pH increased, and declines followed with pH increasing from 5.50 to 9.00. Excellent UV254 removal effect was obtained for PFSS in the 5.50?6.00 coagulation pH range, and the highest removal efficiency was 57.69% when pH 5.50. PFS had the optimum UV254 removal effect when pH was 5.00?5.50, and the highest efficiency was obtained at pH 5.50. Comparing PFSS and PFS, the former had better turbidity removal effect under the same coagulation pH. In the pH range of 5.50?7.50, PFSS showed higher UV254 removal efficiency, while PFS had better performance under acidic and alkaline conditions.The variations of zeta potential of flocs formed by PFSS and PFS under different pH conditions are shown in Figure 2. It can be seen that the zeta potential of flocs formed by PFSS and PFS under acidic condition was positive, and the positive charges decreased with the pH increasing. When pH was higher than 6.00, the surface electrical property became negative, which proved the weaker charge neutralization capabilities of the coagulants under alkaline condition. Compared with PFSS, PFS had stronger charge neutralization capability and the value of zeta potential was higher at the same pH. Both coagulants reached the isoelectric points when pH was 5.50?6.00, and both of them had excellent performance in turbidity and UV254 removal.When the coagulation condition is acidic, the density of positive charges in the surfaces of coagulants hydrolysates is quite high. Charge neutralization and complex reaction or chelate reaction between ferric pieces and organic compounds dominate the coagulation mechanism [6]. At the isoelectric point, the colloid surface is electroneutral and the combined action of charge neutralization and chelate reaction results in higher organic removal efficiency. This may be the main reason for that both of the coagulants achieved optimum UV254 removal effect when pH 5.50. However, both coagulants did not perform well in organic matter removal when pH 4.00. It may be explained by the fact that when the coagulation condition is acidic, the carboxyl groups of organic compounds are difficult to be hydrolyzed due to the high concentration of H+; furthermore, H+ could react with organic molecules which competed with the complex reaction between ferric pieces and organic compounds [16]. Under neutral and alkaline conditions, parts of the colloid particles and organic compounds are absorbed by the hydrolysis products of coagulants, and parts of them are swept and coprecipitated with the coagulants hydrolysates.In this case, the reaction between OH? and ferric pieces interferes with the formation of ferric-organism complexes [17], and thus organic compounds removal efficiencies were lower. 2.2 Influence of pH on floc formation The particle diameters in the suspension were determined on-line via a laser diffraction instrument Mastersizer 2000 during the coagulation period. Figure 3 shows the variation of median particle diameters (d0.5) of the flocs formed by PFSS and PFS at different pH versus coagulation time (0?16 min).The floc formation process can be considered to be a rapid growth stage followed by a stable growth stage. The floc growth rate can be expressed by the steady-state floc sizes (d0) and the growth time needs to reach the steadystate (Table 1). The results show that pH had a great influence on floc growth rate in PFSS coagulation process.When pH was 4.00, after coagulation for 6.5 min, the d0.5 of PFSS flocs reached the steady size of 906.8 μm, and growth rate was 136.0 μm/min. Increasing coagulation pH, the growth time of PFSS flocs became shorter while the growth rate increased. Increasing pH to 9.00, the growth time of PFSS flocs was 3 min, with a growth rate up to 303.0μm/min. For PFS, the floc growth rate was lower when pH 4.00, and did not reach the steady-state during the 16 min coagulation period, while pH had little effect on floc formation when the coagulation pH was 5.50 and above. Comparing the two coagulants, the floc sizes of PFSS were larger and the steady d0.5 was about 900 μm, while the floc sizes of PFS were around 500 μm. Under the same coagulation pH conditions, the growth time of PFSS flocs was shorter than that of PFS flocs, and the growth rate was 3?5 times that of PFS flocs.Floc formation process is related to the coagulation mechanism. The particle sizes of colloids in raw water are distributed in the range of 0.2?20 μm, and the median particle diameter was 3.2±0.5 μm. At the moment when coagulants are dosed, the colloid particles in the raw water contact with the ferric pieces rapidly, and the colloids were destabilized because of the charge neutralization. During the rapid stirring period, the unstable colloids collide with each other and aggregate into large flocs. In the slow stirring period, flocs grow in the following ways: parts of the organic compounds and colloid particles are absorbed by the coagulants hydrolysates, and parts of them are swept with the coagulants hydrolysates. Take PFSS as an example, flocs grew slowly when pH 4.00 because of the stronger charge neutralization capability but weaker sweep capability of the coagulant hydrolysis products. After stirring at 40 r/min for 5 min, the particle diameters of the suspension are distributed in the range of 30?1200 μm, and d0.5 was 361.3 μm. Under the alkaline conditions, the hydrolysates of PFSS coagulants swept the colloid particles and micro-flocs, and aggregates with large sizes were formed rapidly. When the coagulation pH was 9.00, flocs with d0.5 of 912.2 μm were formed and most of the particle sizes ranged from 460?1500 μm. 2.3 Influence of pH on floc breakage and re-growth After the slow stirring phase, the preformed flocs were exposed to a stronger shear force of 200 r/min for 15 min, and the flocs were broken. Then slow shear speed of 40r/min was reintroduced for a further 15 min, and the broken flocs began to reaggregate. The variation of d0.5 during the whole period is displayed in Figure 4. As can be seen, applying the shear force for 30 s, the d0.5 of flocs dropped drastically, and then a gentle decrease followed. When the shear speed was slowing down, the broken flocs reaggregated and reached a new steady-state. The breakage and re-growth capability are usually evaluated by floc breakage factor (Bf) and recovery factor (Rf) bymany researchers, which are defined as follows ： （1） （2） where d0 is the average floc size of the steady phase before breakage, d1 is the floc size after floc breakage, and d2 is the floc size after reaggregating to a new steady phase.The breakage and recovery factors of flocs preformed by PFSS and PFS under the experimental pH conditions are listed in Table 2. The results show that, with the same shear force and shear period, the breakage factors of flocs were related to the coagulation pH. The higher the pH value, the larger the floc breakage factors. The d0.5 of flocs formed by PFSS at pH 4.00 decreased from 906.8 μm to 294.5 μm after exposure to 200 r/min shear speed for 15 min, and the breakage factor was 68.6%. When the coagulation pH was 9.00, the d0.5 was 214.4 μm and Bf was 76.0%. Compared with PFSS, PFS flocs had stronger floc strength when pH 4.00, and the Bf was 16.7%, while PFS flocs formed at higher pH gave higher breakage factors than PFSS.The broken flocs which reaggregated after slow stir were reintroduced, and the recovery degree was related to the floc formation conditions. The PFS flocs which were preformed at pH 4.00 had the strongest re-growth capability; the d0.5 of recovered flocs was 514.9 μm, which was larger than the 328.4 μm d0.5 of un-broken flocs, and the calculated recovery factor was 582.4%. With the coagulation pH increasing, the Rf of PFSS flocs increased at first and then decreased.When pH 4.00, the PFSS flocs had the largest Rf, i.e. 33.2%,while the recovery factor was 21.6% at the 7.00 coagulation pH. Compared with PFSS flocs, the flocs formed by PFS had larger recovery factors under the same pH, which indicated stronger re-growth capabilities.Floc breakage and re-growth are related to floc formation processes. As shown in Figure 2, under the same coagulation pH, the zeta potentials of PFS flocs were much higher than those of PFSS flocs, which indicates stronger charge neutralization abilities. Because of the larger molecular weight, special ramal sharp and larger surface areas of hydrolysis products [20,21], the absorption capability of PFSS is much stronger than that of PFS. Charge neutralization dominates the PFS coagulation mechanism, while the main coagulation mechanisms of PFSS are the absorption of organic compounds and sweep flocculation. This may be the main reason for that PFSS flocs and PFS flocs had different performance during the breakage and re-growth periods. When charge neutrality dominates the coagulation mechanism, the negative charges in the colloid surfaces are neutralized by the positive charged coagulants and the destabilized colloids aggregate to form flocs. 8